1874035 - Profiler "render reason" strings are broken

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[Markus Stange [:mstange]]

Example profile: https://share.firefox.dev/47Apb1U

The render reasons in the profiler markers no longer have readable strings. Now it says things like "Render reason RenderReasons(32768)" instead of "Render reason VSYNC".

https://searchfox.org/mozilla-central/rev/b1a029fadaaabb333d8139f9ec3924a20c0c941f/gfx/wr/webrender/src/renderer/mod.rs#1634-1637

if add_markers {
    let event_str = format!("Render reason {:?}", reason_bit);
    add_event_marker(&event_str);
}

It looks like the Debug implementation on bitfields has changed.

Comment 1

[Florian Quèze [:florian]]

Almost filed a duplicate. mozregression says: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=d0a48f87ca55781281108541c014ad59d6334268&tochange=b3d4dd6d5b436ace9de5430fd3ebdd2869014ce8 -> bug 1852209

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1852209

:glandium, since you are the author of the regressor, bug 1852209, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 3

[Mike Hommey [:glandium]]

Ah, this is happening for all the types with a Debug derive where the "custom derive" method is used (https://docs.rs/bitflags/latest/bitflags/#custom-derives)

Comment 4

[Bob Hood [:bhood]]

Mike, could you please assign Priority/Severity ratings to this report when you get a chance?

Comment 5

[Mike Hommey [:glandium]]

Attachment: Bug 1874035 - Add custom Debug derives for bitflags with custom derives.

bitflags 2 has a shortcoming with using custom derives: you can't use
custom derives (for e.g. MallocSizeOf) at the same time as bitflags's for
the derives it supports.
See https://github.com/bitflags/bitflags/issues/395

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/45bd6cc1bf74
Add custom Debug derives for bitflags with custom derives. r=gfx-reviewers,emilio,ErichDonGubler

Comment 7

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/45bd6cc1bf74

Comment 8

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:glandium, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox123 to wontfix.

For more information, please visit BugBot documentation.

Comment 9

[Mike Hommey [:glandium]]

Marcus, what do you think?

Comment 10

[Markus Stange [:mstange]]

I'm ok with this being broken on Release a bit more. I mostly look at profiles from Nightly.